Quantitative Estimation of Promoter Activity in Cannabis sativa Using Agroinfiltration-Based Transient Gene Expression

To properly assess promoter activity, which is critical for understanding biosynthetic pathways in different plant species, we use agroinfiltration-based transient gene expression assay. We compare the activity of several known promoters in Nicotiana benthamiana with their activity in Cannabis sativa (both hemp and medicinal cannabis), which has attracted much attention in recent years for its industrial, medicinal, and recreational properties. Here we describe an optimized protocol for transient expression in Cannabis combined with a ratiometric GUS reporter system that allows more accurate evaluation of promoter activity and reduces the effects of variable infiltration efficiency.

The virtual aging brain: Causal inference supports interhemispheric dedifferentiation in healthy aging

The mechanisms of cognitive decline and its variability during healthy aging are not fully understood, but have been associated with reorganization of white matter tracts and functional brain networks. Here, we built a brain network modeling framework to infer the causal link between structural connectivity and functional architecture and the consequent cognitive decline in aging. By applying in-silico interhemispheric degradation of structural connectivity, we reproduced the process of functional dedifferentiation during aging. Thereby, we found the global modulation of brain dynamics by structural connectivity to increase with age, which was steeper in older adults with poor cognitive performance. We validated our causal hypothesis via a deep-learning Bayesian approach. Our results might be the first mechanistic demonstration of dedifferentiation during aging leading to cognitive decline.

Integrating psychosocial variables and societal diversity in epidemic models for predicting COVID-19 transmission dynamics

During the current COVID-19 pandemic, governments must make decisions based on a variety of information including estimations of infection spread, health care capacity, economic and psychosocial considerations. The disparate validity of current short-term forecasts of these factors is a major challenge to governments. By causally linking an established epidemiological spread model with dynamically evolving psychosocial variables, using Bayesian inference we estimate the strength and direction of these interactions for German and Danish data of disease spread, human mobility, and psychosocial factors based on the serial cross-sectional COVID-19 Snapshot Monitoring (COSMO; N = 16,981). We demonstrate that the strength of cumulative influence of psychosocial variables on infection rates is of a similar magnitude as the influence of physical distancing. We further show that the efficacy of political interventions to contain the disease strongly depends on societal diversity, in particular group-specific sensitivity to affective risk perception. As a consequence, the model may assist in quantifying the effect and timing of interventions, forecasting future scenarios, and differentiating the impact on diverse groups as a function of their societal organization. Importantly, the careful handling of societal factors, including support to the more vulnerable groups, adds another direct instrument to the battery of political interventions fighting epidemic spread.

RateML: A Code Generation Tool for Brain Network Models

Whole brain network models are now an established tool in scientific and clinical research, however their use in a larger workflow still adds significant informatics complexity. We propose a tool, RateML, that enables users to generate such models from a succinct declarative description, in which the mathematics of the model are described without specifying how their simulation should be implemented. RateML builds on NeuroML's Low Entropy Model Specification (LEMS), an XML based language for specifying models of dynamical systems, allowing descriptions of neural mass and discretized neural field models, as implemented by the Virtual Brain (TVB) simulator: the end user describes their model's mathematics once and generates and runs code for different languages, targeting both CPUs for fast single simulations and GPUs for parallel ensemble simulations. High performance parallel simulations are crucial for tuning many parameters of a model to empirical data such as functional magnetic resonance imaging (fMRI), with reasonable execution times on small or modest hardware resources. Specifically, while RateML can generate Python model code, it enables generation of Compute Unified Device Architecture C++ code for NVIDIA GPUs. When a CUDA implementation of a model is generated, a tailored model driver class is produced, enabling the user to tweak the driver by hand and perform the parameter sweep. The model and driver can be executed on any compute capable NVIDIA GPU with a high degree of parallelization, either locally or in a compute cluster environment. The results reported in this manuscript show that with the CUDA code generated by RateML, it is possible to explore thousands of parameter combinations with a single Graphics Processing Unit for different models, substantially reducing parameter exploration times and resource usage for the brain network models, in turn accelerating the research workflow itself. This provides a new tool to create efficient and broader parameter fitting workflows, support studies on larger cohorts, and derive more robust and statistically relevant conclusions about brain dynamics.

High-resolution Virtual Brain Modeling Personalizes Deep Brain Stimulation for Treatment-Resistant Depression: Spatiotemporal Response Characteristics Following Stimulation of Neural Fiber Pathways

Over the past 15 years, deep brain stimulation (DBS) has been actively investigated as a groundbreaking therapy for patients with treatment-resistant depression (TRD); nevertheless, outcomes have varied from patient to patient, with an average response rate of ∼50%. The engagement of specific fiber tracts at the stimulation site has been hypothesized to be an important factor in determining outcomes, however, the resulting individual network effects at the whole-brain scale remain largely unknown. Here we provide a computational framework that can explore each individual's brain response characteristics elicited by selective stimulation of fiber tracts. We use a novel personalized in-silico approach, the Virtual Big Brain, which makes use of high-resolution virtual brain models at a mm-scale and explicitly reconstructs more than 100 000 fiber tracts for each individual. Each fiber tract is active and can be selectively stimulated. Simulation results demonstrate distinct stimulus-induced event-related potentials as a function of stimulation location, parametrized by the contact positions of the electrodes implanted in each patient, even though validation against empirical patient data reveals some limitations (i.e., the need for individual parameter adjustment, and differential accuracy across stimulation locations). This study provides evidence for the capacity of personalized high-resolution virtual brain models to investigate individual network effects in DBS for patients with TRD and opens up novel avenues in the personalized optimization of brain stimulation.

Neuronal Cascades Shape Whole-Brain Functional Dynamics at Rest

At rest, mammalian brains display remarkable spatiotemporal complexity, evolving through recurrent functional connectivity (FC) states on a slow timescale of the order of tens of seconds. While the phenomenology of the resting state dynamics is valuable in distinguishing healthy and pathologic brains, little is known about its underlying mechanisms. Here, we identify neuronal cascades as a potential mechanism. Using full-brain network modeling, we show that neuronal populations, coupled via a detailed structural connectome, give rise to large-scale cascades of firing rate fluctuations evolving at the same time scale of resting-state networks (RSNs). The ignition and subsequent propagation of cascades depend on the brain state and connectivity of each region. The largest cascades produce bursts of blood oxygen level-dependent (BOLD) co-fluctuations at pairs of regions across the brain, which shape the simulated RSN dynamics. We experimentally confirm these theoretical predictions. We demonstrate the existence and stability of intermittent epochs of FC comprising BOLD co-activation (CA) bursts in mice and human functional magnetic resonance imaging (fMRI). We then provide evidence for the existence and leading role of the neuronal cascades in humans with simultaneous EEG/fMRI recordings. These results show that neuronal cascades are a major determinant of spontaneous fluctuations in brain dynamics at rest.

Connectivity Between Brain Networks Dynamically Reflects Cognitive Status of Parkinson's Disease: A Longitudinal Study

BACKGROUND

Cognitive impairment in Parkinson's disease (PD) is associated with altered connectivity of the resting state networks (RSNs). Longitudinal studies in well cognitively characterized PD subgroups are missing.

OBJECTIVES

To assess changes of the whole-brain connectivity and between-network connectivity (BNC) of large-scale functional networks related to cognition in well characterized PD patients using a longitudinal study design and various analytical methods.

METHODS

We explored the whole-brain connectivity and BNC of the frontoparietal control network (FPCN) and the default mode, dorsal attention, and visual networks in PD with normal cognition (PD-NC, n = 17) and mild cognitive impairment (PD-MCI, n = 22) as compared to 51 healthy controls (HC). We applied regions of interest-based, partial least squares, and graph theory based network analyses. The differences among groups were analyzed at baseline and at the one-year follow-up visit (37 HC, 23 PD all).

RESULTS

The BNC of the FPCN and other RSNs was reduced, and the whole-brain analysis revealed increased characteristic path length and decreased average node strength, clustering coefficient, and global efficiency in PD-NC compared to HC. Values of all measures in PD-MCI were between that of HC and PD-NC. After one year, the BNC was further increased in the PD-all group; no changes were detected in HC. No cognitive domain z-scores deteriorated in either group.

CONCLUSION

As compared to HC, PD-NC patients display a less efficient transfer of information globally and reduced BNC of the visual and frontoparietal control network. The BNC increases with time and MCI status, reflecting compensatory efforts.

Spatial constraints on the diffusion of religious innovations: The case of early Christianity in the Roman Empire

Christianity emerged as a small and marginal movement in the first century Palestine and throughout the following three centuries it became highly visible in the whole Mediterranean. Little is known about the mechanisms of spreading innovative ideas in past societies. Here we investigate how well the spread of Christianity can be explained as a diffusive process constrained by physical travel in the Roman Empire. First, we combine a previously established model of the transportation network with city population estimates and evaluate to which extent the spatio-temporal pattern of the spread of Christianity can be explained by static factors. Second, we apply a network-theoretical approach to analyze the spreading process utilizing effective distance. We show that the spread of Christianity in the first two centuries closely follows a gravity-guided diffusion, and is substantially accelerated in the third century. Using the effective distance measure, we are able to suggest the probable path of the spread. Our work demonstrates how the spatio-temporal patterns we observe in the data can be explained using only spatial constraints and urbanization structure of the empire. Our findings also provide a methodological framework to be reused for studying other cultural spreading phenomena.

Robustness of Representative Signals Relative to Data Loss Using Atlas-Based Parcellations

Parcellation-based approaches are an important part of functional magnetic resonance imaging data analysis. They are a necessary processing step for sorting data in structurally or functionally homogenous regions. Real functional magnetic resonance imaging datasets usually do not cover the atlas template completely; they are often spatially constrained due to the physical limitations of MR sequence settings, the inter-individual variability in brain shape, etc. When using a parcellation template, many regions are not completely covered by actual data. This paper addresses the issue of the area coverage required in real data in order to reliably estimate the representative signal and the influence of this kind of data loss on network analysis metrics. We demonstrate this issue on four datasets using four different widely used parcellation templates. We used two erosion approaches to simulate data loss on the whole-brain level and the ROI-specific level. Our results show that changes in ROI coverage have a systematic influence on network measures. Based on the results of our analysis, we recommend controlling the ROI coverage and retaining at least 60% of the area in order to ensure at least 80% of explained variance of the original signal.

Large-scale cortico-subcortical functional networks in focal epilepsies: The role of the basal ganglia

Objectives

The aim was to describe the contribution of basal ganglia (BG) thalamo-cortical circuitry to the whole-brain functional connectivity in focal epilepsies.

Methods

Interictal resting-state fMRI recordings were acquired in 46 persons with focal epilepsies. Of these 46, 22 had temporal lobe epilepsy: 9 left temporal (LTLE), 13 right temporal (RTLE); 15 had frontal lobe epilepsy (FLE); and 9 had parietal/occipital lobe epilepsy (POLE). There were 20 healthy controls. The complete weighted network was analyzed based on correlation matrices of 90 and 194 regions. The network topology was quantified on a global and regional level by measures based on graph theory, and connection-level changes were analyzed by the partial least square method.

Results

In all patient groups except RTLE, the shift of the functional network topology away from random was observed (normalized clustering coefficient and characteristic path length were higher in patient groups than in controls). Links contributing to this change were found in the cortico-subcortical connections. Weak connections (low correlations) consistently contributed to this modification of the network. The importance of regions changed: decreases in the subcortical areas and both decreases and increases in the cortical areas were observed in node strength, clustering coefficient and eigenvector centrality in patient groups when compared to controls. Node strength decreases of the basal ganglia, i.e. the putamen, caudate, and pallidum, were displayed in LTLE, FLE, and POLE. The connectivity within the basal ganglia–thalamus circuitry was not disturbed; the disturbance concerned the connectivity between the circuitry and the cortex.

Significance

Focal epilepsies affect large-scale brain networks beyond the epileptogenic zones. Cortico-subcortical functional connectivity disturbance was displayed in LTLE, FLE, and POLE. Significant changes in the resting-state functional connectivity between cortical and subcortical structures suggest an important role of the BG and thalamus in focal epilepsies.

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Focal epilepsies affect large-scale brain networks beyond the epileptogenic zones.

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The functional network topology shifted away from random in focal epilepsies.

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Subcortico-cortical connectivity decreased in epilepsy due to changes in weak links.

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Basal ganglia–thalamus circuitry connectivity was not disturbed in focal epilepsy.

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The connectivity between basal ganglia-thalamus circuitry and cortex was affected.

Oblong Cup in the Management of Aseptic Loosening of the Acetabular Component in Total Hip Replacement

Background and Aims:

At present, revision surgery of a total hip replacement is a major problem that must be dealt with by all orthopedic facilities. Aseptic loosening of the acetabular component is often associated with destruction of the original spherical shape of the acetabulum and the formation of bone defects. An orthopedist faces the challenge of acetabular revision and stable fixation of the new acetabular component in an effort to re-establish the functioning of the hip replacement.

Material and Methods:

The authors evaluated a group of 74 patients in whom they implanted an oblong revision cup due to aseptic loosening of the acetabular component from August 2000 until December 2003. The mean duration of the follow-up period was 63 months (ranging from 38 to 78 months).

Results and Conclusions:

The authors reported very good results from the use of this implant, where osteointegration and good functional outcome evaluated according to the Harris Hip Score (HHS) were achieved in 95% of cases. The long-term outcome should be the subject of further investigation.

Updating algal evolutionary relationships through plastid genome sequencing: did alveolate plastids emerge through endosymbiosis of an ochrophyte?

Algae with secondary plastids of a red algal origin, such as ochrophytes (photosynthetic stramenopiles), are diverse and ecologically important, yet their evolutionary history remains controversial. We sequenced plastid genomes of two ochrophytes, Ochromonas sp. CCMP1393 (Chrysophyceae) and Trachydiscus minutus (Eustigmatophyceae). A shared split of the clpC gene as well as phylogenomic analyses of concatenated protein sequences demonstrated that chrysophytes and eustigmatophytes form a clade, the Limnista, exhibiting an unexpectedly elevated rate of plastid gene evolution. Our analyses also indicate that the root of the ochrophyte phylogeny falls between the recently redefined Khakista and Phaeista assemblages. Taking advantage of the expanded sampling of plastid genome sequences, we revisited the phylogenetic position of the plastid of Vitrella brassicaformis, a member of Alveolata with the least derived plastid genome known for the whole group. The results varied depending on the dataset and phylogenetic method employed, but suggested that the Vitrella plastids emerged from a deep ochrophyte lineage rather than being derived vertically from a hypothetical plastid-bearing common ancestor of alveolates and stramenopiles. Thus, we hypothesize that the plastid in Vitrella, and potentially in other alveolates, may have been acquired by an endosymbiosis of an early ochrophyte.

Growth and stress response in Arabidopsis thaliana, Nicotiana benthamiana, Glycine max, Solanum tuberosum and Brassica napus cultivated under polychromatic LEDs

BACKGROUND

The use of light emitting diodes (LEDs) brings several key advantages over existing illumination technologies for indoor plant cultivation. Among these are that LEDs have predicted lifetimes from 50-100.000 hours without significant drops in efficiency and energy consumption is much lower compared to traditional fluorescent tubes. Recent advances allow LEDs to be used with customized wavelengths for plant growth. However, most of these LED growth systems use mixtures of chips emitting in several narrow wavelengths and frequently they are not compatible with existing infrastructures. This study tested the growth of five different plant species under phosphor coated LED-chips fitted into a tube with a standard G13 base that provide continuous visible light illumination with enhanced blue and red light.

RESULTS

The LED system was characterized and compared with standard fluorescence tubes in the same cultivation room. Significant differences in heat generation between LEDs and fluorescent tubes were clearly demonstrated. Also, LED lights allowed for better control and stability of preset conditions. Physiological properties such as growth characteristics, biomass, and chlorophyll content were measured and the responses to pathogen assessed for five plant species (both the model plants Arabidopsis thaliana, Nicotiana bentamiana and crop species potato, oilseed rape and soybean) under the different illumination sources.

CONCLUSIONS

We showed that polychromatic LEDs provide light of sufficient quality and intensity for plant growth using less than 40% of the electricity required by the standard fluorescent lighting under test. The tested type of LED installation provides a simple upgrade pathway for existing infrastructure for indoor plant growth. Interestingly, individual plant species responded differently to the LED lights so it would be reasonable to test their utility to any particular application.

The mitochondrion-like organelle of Trimastix pyriformis contains the complete glycine cleavage system

All eukaryotic organisms contain mitochondria or organelles that evolved from the same endosymbiotic event like classical mitochondria. Organisms inhabiting low oxygen environments often contain mitochondrial derivates known as hydrogenosomes, mitosomes or neutrally as mitochondrion-like organelles. The detailed investigation has shown unexpected evolutionary plasticity in the biochemistry and protein composition of these organelles in various protists. We investigated the mitochondrion-like organelle in Trimastix pyriformis, a free-living member of one of the three lineages of anaerobic group Metamonada. Using 454 sequencing we have obtained 7 037 contigs from its transcriptome and on the basis of sequence homology and presence of N-terminal extensions we have selected contigs coding for proteins that putatively function in the organelle. Together with the results of a previous transcriptome survey, the list now consists of 23 proteins - mostly enzymes involved in amino acid metabolism, transporters and maturases of proteins and transporters of metabolites. We have no evidence of the production of ATP in the mitochondrion-like organelle of Trimastix but we have obtained experimental evidence for the presence of enzymes of the glycine cleavage system (GCS), which is part of amino acid metabolism. Using homologous antibody we have shown that H-protein of GCS localizes into vesicles in the cell of Trimastix. When overexpressed in yeast, H- and P-protein of GCS and cpn60 were transported into mitochondrion. In case of H-protein we have demonstrated that the first 16 amino acids are necessary for this transport. Glycine cleavage system is at the moment the only experimentally localized pathway in the mitochondrial derivate of Trimastix pyriformis.

The plastid genome of Eutreptiella provides a window into the process of secondary endosymbiosis of plastid in euglenids

Euglenids are a group of protists that comprises species with diverse feeding modes. One distinct and diversified clade of euglenids is photoautotrophic, and its members bear green secondary plastids. In this paper we present the plastid genome of the euglenid Eutreptiella, which we assembled from 454 sequencing of Eutreptiella gDNA. Comparison of this genome and the only other available plastid genomes of photosynthetic euglenid, Euglena gracilis, revealed that they contain a virtually identical set of 57 protein coding genes, 24 genes fewer than the genome of Pyramimonas parkeae, the closest extant algal relative of the euglenid plastid. Searching within the transcriptomes of Euglena and Eutreptiella showed that 6 of the missing genes were transferred to the nucleus of the euglenid host while 18 have been probably lost completely. Euglena and Eutreptiella represent the deepest bifurcation in the photosynthetic clade, and therefore all these gene transfers and losses must have happened before the last common ancestor of all known photosynthetic euglenids. After the split of Euglena and Eutreptiella only one additional gene loss took place. The conservation of gene content in the two lineages of euglenids is in contrast to the variability of gene order and intron counts, which diversified dramatically. Our results show that the early secondary plastid of euglenids was much more susceptible to gene losses and endosymbiotic gene transfers than the established plastid, which is surprisingly resistant to changes in gene content.

Sound-speed image reconstruction in sparse-aperture 3-D ultrasound transmission tomography

The paper is focused on sound-speed image reconstruction in 3-D ultrasound transmission tomography. Along with ultrasound reflectivity and the attenuation coefficient, sound speed is an important parameter which is related to the type and pathological state of the imaged tissue. This is important in the intended application, breast cancer diagnosis. In contrast to 2-D ultrasound transmission tomography systems, a 3-D system can provide an isotropic spatial resolution in the x-, y-, and z-directions in reconstructed 3-D images of ultrasound parameters. Several challenges must, however, be addressed for 3-D systems-namely, a sparse transducer distribution, low signal-to-noise ratio, and higher computational complexity. These issues are addressed in terms of sound-speed image reconstruction, using edge-preserving regularized algebraic reconstruction in combination with synthetic aperture focusing. The critical points of the implementation are also discussed, because they are crucial to enable a complete 3-D image reconstruction. The methods were tested on a synthetic data set and on data sets measured with the Karlsruhe 3-D ultrasound computer tomography (USCT) I prototype using phantoms. The sound-speed estimates in the reconstructed volumes agreed with the reference values. The breast-phantom outlines and the lesion-mimicking objects were also detectable in the resulting sound-speed volumes.

Purification and characterization of hydroquinone dioxygenase from Sphingomonas sp. strain TTNP3

Hydroquinone-1,2-dioxygenase, an enzyme involved in the degradation of alkylphenols in Sphingomonas sp. strain TTNP3 was purified to apparent homogeneity. The extradiol dioxygenase catalyzed the ring fission of hydroquinone to 4-hydroxymuconic semialdehyde and the degradation of chlorinated and several alkylated hydroquinones. The activity of 1 mg of the purified enzyme with unsubstituted hydroquinone was 6.1 μmol per minute, the apparent K_m 2.2 μM. ICP-MS analysis revealed an iron content of 1.4 moles per mole enzyme. The enzyme lost activity upon exposure to oxygen, but could be reactivated by Fe(II) in presence of ascorbate. SDS-PAGE analysis of the purified enzyme yielded two bands of an apparent size of 38 kDa and 19 kDa, respectively. Data from MALDI-TOF analyses of peptides of the respective bands matched with the deduced amino acid sequences of two neighboring open reading frames found in genomic DNA of Sphingomonas sp strain TTNP3. The deduced amino acid sequences showed 62% and 47% identity to the large and small subunit of hydroquinone dioxygenase from Pseudomonas fluorescens strain ACB, respectively. This heterotetrameric enzyme is the first of its kind found in a strain of the genus Sphingomonas sensu latu.

[Plate osteosynthesis in vancouver type b1 and b2 periprosthetic fractures]

PURPOSE OF THE STUDY

In a retrospective study we evaluated the results of plate osteosynthesis for treatment of periprosthetic femoral fractures classified as Vancouver types B1 and B2.

MATERIAL AND METHODS

The group comprised 19 patients with post-operative periprosthetic fractures treated by open reduction and internal fixation with plate osteosynthesis at our department between the beginning of 2004 and June 2007. Perioperative fractures were not included. The average age of the patients was 72.0 (range, 53 to 88) years. A locking compression plate (PCL) was used in 16 patients. The average follow-up was 21 months, with 6 months at least.We evaluated radiographs of the fracture and, in the majority of cases, also those before a periprosthetic fracture occurred. We focussed on the signs of potential femoral component loosening and the course of fracture line; fractures were classified according to the Vancouver classification system. Follow-up included both clinical and radiographic examination.

RESULTS

Thirteen patients showed bone union and a good functional outcome. One patient was present at follow-up only once and was not included in the final evaluation. Non-union was recorded in five patients (27.7 %), marked implant migration occurred in three (all had type B2 fracture) and osteosynthesis failed in two patients.

DISCUSSION

We consider the Vancouver classification to be the most suitable classification system. The relatively high proportion of non-union fractures can be accounted for by an inappropriate indication for osteosynthesis in fractures with stem loosening.The assessment of stem stability based on a radiograph only may, in some cases, be questionable; therefore, if doubtful, we prefer an intra-operative evaluation of implant stability.We also discuss a contribution of angle-stable plates to the osteosynthesis of periprosthetic fractures as well as their bone fixation technique.

CONCLUSIONS

Plate osteosynthesis is a suitable method for treatment of periprosthetic fractures if there is a stable femoral component. LPC implants are not discriminative enough in the range of indications for plate osteosynthesis.The use of plate osteosynthesis in a total hip arthroplasty with signs of loosening is bound to lead to acceleration of loosening and stem migration, and may even result in plate breakage or its expulsion. This implies that, in such THAs, plate osteosynthesis can only be carried out as a palliative procedure in immobile and severely ill old patients. Key words: periprosthetic fractures, total hip arthroplasty, revision total hip arthroplasty, plate fixation, LCP, Vancouver classification.

[Total hip arthroplasty in post-dysplastic hip arthritis. Can type and position of the acetabular component influence longevity of the prosthesis?]

PURPOSE OF THE STUDY

The aim of the study was a retrospective evaluation of our patients with post-dysplastic hips treated by cemented or non-cemented total hip arthroplasty (THA) in order to ascertain which type and position of the acetabular component was most effective.

MATERIAL

In the years 1999-2002, 111 THA procedures were performed in 93 patients, 76 women and 17 men, with post-dysplastic hip arthritis. The average age of the patients at the time of implantation was 52.6 years. On the basis of pre-operative radiographic findings, the patients' conditions were evaluated using the Hartofilakidis classification into three disease categories: dysplasia, low dislocation and high dislocation, and the patients were placed in two groups. Group 1 included 78 patients, and group 2 comprised 26 patients. None of our patients was classified as having high dislocation. Thirty-nine of these patients had previously undergone surgery for dysplastic hips.

METHODS

A total of 104 THAs were evaluated, because radiographic data was incomplete in seven cases. In addition to X-ray findings, the prosthesis type (cemented, hybrid, non-cemented), post-operative complications and signs of loosening were included in the evaluation. Clinical outcomes were assessed by the Harris score. The follow-up terminating on 31st December 2005 was 67 months on the average.

RESULTS

In group 1 patients, the average Harris score increased from 38.6 to 80.3 points and in group 2 patients from 35.5 to 84.9 points, mostly with excellent and good results. In 72.1 % of the hips, a press-fit acetabular component was implanted. In 55.8 % of the cases, the acetabular component was implanted off the anatomical center of rotation, into the high hip center, with the range from 9 to 20 mm and an average of 15 mm. The average limb lengthening was 2.5 cm, ranging from 1.0 to 3.5 cm.

CONCLUSIONS

Our results show that it is more effective to use non-cemented THA for post-dysplastic hips. The implantation of a noncemented acetabular component into the high center provides better covering of the cup with solid bone, without the necessity of cotyloplasty or structural graft use. Also, it does not markedly affect hip function or patients' subjective feelings.

[Management of pseudoarthrosis of the navicular bone of the wrist using the Synthes 3.0 screw]

The authors compare their results of the management of the pseudoarthrosis of the navicular bone of the wrist with those reported in the literature. The study group included 21 patients and the Synthes 3.0 mm was applied. The authors concentrate on both technical and biological aspects of the therapy, mainly on an appropriate choice of the procedure, quality of the management of the surfaces of the pseudoarthrosis and significance of correct introduction of the device. The rate of the healed pseudoarthroses reached 85.7% in their patient trial group. They conclude that the main prerequisites for a successful outcome are the biological status of the pseudoarthrosis and a thorough management of the pseudoarthrosis surfaces, rather than a type of the implant.

Determination of genetic differences between fluid and nonfluid variants of Clavibacter michiganensis subsp. sepedonicus using rep-PCR technique

Testing of 23 isolates of Clavibacter michiganensis subsp. sepedonicus for analysis by rep-PCR (using BOX, ERIC, REP primer sets) was used for the purpose of localization of genetic markers for fluid and/or nonfluid strains. None of the primer sets was successful in detecting genetic differences between the isolates and no polymorphism was generated.

Comparison of genetic variability between Czech and foreign isolates of phytopathogenic bacteria Clavibacter michiganensis subsp. sepedonicus by Rep-PCR technique

Repetitive-sequence-based polymerase chain reaction (Rep-PCR) method was used for analysis of genetic variability among bacterial populations from different world locations. Collection of 26 Czech and 13 foreign strains of Clavibacter michiganensis subsp. sepedonicus was amplified using BOX primer targeting to repetitive motif occurring in eubacterial genomes. Genetic fingerprints were visually compared and statistically evaluated by cluster analysis. Genetic similarity was estimated to be approximately 80% among all tested strains. Populations of these bacteria seem to be highly homogeneous; potential influence of geographic origin was not confirmed.

[Analysis of complications in the treatment of fracture leg fractures with unreamed intramedullary nailing]

Based on their group of 52 patients the authors analyze the complications they encountered in the treatment of crural fractures by a not predrilled intramedullary nail. Consistent with the literature they found that this method is successful in the treatment of closed and open fractures of the crural diaphysis. They mention, however, a relatively high percentage of complications which in the long run are not a impediment for healing of the fracture but influence it. In the discussion these complications are analyzed in detail in an attempt to find a solution and to avoid them in future patients. They conclude that even this relatively simple and effective method of fractures of the crural diaphysis has its pitfalls and its indication and implementation call for much attention.

Higher order ferroic switching induced by scanning force microscopy

We present the observation of ferroelastoelectric switching in a ferroelectric material. It is achieved in barium titanate thin film by simultaneously applying electric field and compressive stress with the tip of a scanning force microscope. For low compressive stresses, the presented measurements reveal classical ferroelectric domain reversal, i.e., the spontaneous polarization is aligned parallel to the applied electric field. However, for high compressive stresses the direction of polarization after switching is antiparallel to the poling field, demonstrating ferroelastoelectric switching.

[The Sauvé-Kapandji operation in the treatment of traumatic disorder of the distal radioulnar joint]

The authors describe in a group of 22 patients their experience with Sauvé-Kapandji's operation in posttraumatic damage of the distal radioulnar joint. They analyze the causes of affection of the distal radioulnar joint, discuss the functional anatomy of this joint and describe the technique of operation. In the discussion they deal with possible complications and analyze in detail their results. They suggest a pattern of evaluation of the results of surgery based on objective and subjective findings. In the conclusion they mention the satisfactory results of this operation if the correct surgical technique is used and careful indication of the operation is made.

[The First Results of 360 degrees Fusion and Video-assisted Minimally Invasive Retroperitoneal Approach to the Lumbar Spine.]

The authors present short-term results of a 360 degrees fusion together with the experience in their own modification of minimally invasive retroperitoneal approach to the lumbar spine. In the course of 1998 and 1999 they operated on the total number of 21 patients using this approach. The anterior approach was considered as part of the combined operation on the lumbar spine which was indicated for degenerative, traumatic, tumorous and iatrogenic instability of the lumbar spine. They evaluated blood loss, duration of the surgery, duration of image intensifier exposure, restoration of the peristalsis, satisfaction of the patient with the operation by means of Visual Analog Scale and in 12 patients who exceeded a twelvemonth of the follow-up also healing of the fusion on dynamic radiographs of the lumbar spine. The results are very optimistic. As compared to a classical approach they achieved low blood loss, short duration of the surgery, a quick restoration of peristalsis and a reduction of postoperative morbidity. An undoubted advantage of the presented technique is the economic thriftiness as concerns special endoscopic devices, retraction frames, microscope, special instruments or expansion devices. During the evaluation of the fusion no development of a nonunion or migration of grafts or cages was recorded. Also the satisfaction of patients after the operation was high and in the following period it even increased. Key words: lumbar spine fusion, retroperitoneal approach, minimally invasive surgery.

[The Matti-Russe method of treatment of ununited fractures of the scaphoid bone]

The authors present their experience with treatment of scaphoid non-unions by the operation according to Matti-Russe. They compare their results with those of other authors and present a relatively high number of successfully treated patients with stable non-unions localized in the midline of the scaphoid bone as well as a high patient satisfaction rate with this method of treatment. The disadvantage of this treatment is long-term cast immobilization of the wrist and poor results in treatment of unstable non-unions and those localized in the proximal portion of the scaphoid bone. They conclude, that at present, it is more effective to support the surgery by osteosynthesis with an adequate implant and thus shorten the immobilization period in a cast.

British-Czech co-operation in a mass casualty incident, Sipovo. From aeromedical evacuation from Bosnia to discharge from Central Military Hospital, Prague

On Thursday 8 January 1998, a Czech Hip helicopter with 21 personnel on board crashed in Bos Krupa, northwest Bosnia, resulting in one of the largest mass casualty incidents involving peacekeepers in Bosnia since conflict broke out there in 1992. Seventeen patients were airlifted from the scene to the British Hospital Squadron in Sipovo, central Bosnia for resuscitation and initial treatment. The next day, six severely injured patients underwent aeromedical evacuation to the Central Military Hospital in Prague. The role of the British Defence Medical Services in this incident was documented in the first article of this two part series. This second article highlights the role of the Czech medical services following aeromedical evacuation of these six patients, and closes the audit trial by documenting the patients' progress and final outcome in Prague.

[Surgical technique of anterior cervical instrumented fusion.]

Authors are presenting their results of anterior cervical instrumented fusion technique on group of 39 patients who were operated on in traumatic and degenerative indications.They present a 97 % fusion rate with minimal complications. Decompression of neural tissues, meticulous shaping of the tricortical autologous bone graft and respecting the physiological alignment of the cervical spine are presented as the most important steps. Application of the Morscher cervical plate is helpful, since it decreases postoperative neck immobilization in orthosis and increases the fusion rate. Key words: anterior instrumented cervical fusion, autologous bone graft, cervical plate.

[External fixation in fractures of distal radius.]

On a group of 30 patients authors present the results they have achieved in the treatment of fractures of distal radius by external fixation. They deal with indications to the treatment of this injury by external fixation and describe in detail the method of such treatment. They discuss the pitfalls of this treatment, potential complications and adequacy of individual types of external fixators. They point out the discrepancy in the evaluation of objective achievements and subjective evaluation of patients. In total they evaluate the results as good and recommend a more consistent diagnostic and therapeutic connsidera-tion of the treatment of these injuries in out-patient departments. Key words: fracture of distal radius, external fixator.

[Initial experience with implantation of a cemented endoprosthesis.]

The authors present their experience with the use of a cemented endoprosthesis of the hip joint Saphir I. During a three-year period they implanted at the Orthopaedic department of the Central Military Hospital in Prague 82 of these endoprostheses with very good mediumterm results. In the first part of the paper they deal with the description of the implant and the range of sizes. They emphasize the satisfactory technical solution of the implant and instruments and the easy technique of implantation. In view of the minimal number of complications and the reasonable price they envisage the use this endoprosthesis in elderly but perspective patients where with regard to osteoporosis and other factors the use of non-cemented endoprosthesis of the hip joint is not indicated. Key words: cemented endoprosthesis of the hip joint, complications of endoprostheses, bone cement.

[Fractures of the distal end of the radius.]

The authors evaluate in a group of 92 patients the results of conservative treatment of fractures of the distal radius. They draw attention to terminological inaccuracies in the evaluation of these fractures. This leads to a relatively high percentage of poor results in their patients, though their results are comparable with those of other authors. As a guideline for treatment they suggest the AO classification and on its basis they propose a more active approach to the treatment of these fractures. Key words: fracture of the distal end of the radius, reposition, redislocation.

[Spontaneously healed pseudoarthrosis of the navicular bone?]

The authors demonstrate a relatively rare case of spontaneous healing of the navicular bone almost four years after the injury. They draw attention to diagnostic difficulties in acute injuries of the wrist and in the diagnosis of a pseudoarthrosis of the navicular bone. Key words: navicular bone of the wrist, pseudoarthrosis of the navicular bone.

[Our experience with bone scintigraphy in the diagnosis of wrist injuries.]

The authors evaluate, based on a group of 40 patients, the contribution of bone scintigraphy to the diagnosis of injuries of the wrist; scintigraphy has a high sensitivity and specificity in fractures of the navicular bone. In addition to injury of that bone the scintigraphic picture of both wrists makes it possible to focus attention also on affections of others structures and thus to contribute to a better diagnosis and treatment of the wrist. The authors found in fractures of the navicular bone in 70 % agreement with the X-ray examination made several weeks after the injury. As regards injuries of other bones of the wrist positive on scintigraphy, the X-ray examination was negative. In the authors' opinion the discrepancy between scintigraphy and X-ray examination is due to the limited possibilities of clasical X-ray pictures. By introduction of more perfect examination methods such as computer tomography and nuclear magnetic resonance in the diagnosis of wrist injuries the number of falsely positive scintigraphic findings should decline. The authors recommend to make scintigraphic examinations during the period between the third day to the end of the third week after the first examination at the ambulatory department. A negative scintigraphic finding rules out injuries of the wrist. Where it is not possible to make a scintigraphic examination, the authors recommend follow-up of the patients for at least six weeks following the first visit of the ambulatory department. Key words: bone scintigraphy, wrist injury, navicular bone of the wrist.